code: def _concordance_ratio(
      num_correct: int, num_tied: int, num_pairs: int
  ) -> float:
      if num_pairs == 0:
          raise ZeroDivisionError("No admissable pairs in the dataset.")
      return (num_correct + num_tied / 2) / num_pairs
  
file_path: lifelines/lifelines/utils/concordance.py
imports: import numpy
  from lifelines.utils.btree import _BTree
label_desc: Use image node_id 3 for calling a global function with example usage: _concordance_ratio(num_correct, num_tied, num_pairs) and returns: unknown